The present invention relates to methods for treating powders of pigment, etc., and an apparatus used therefor.
Powders used to coatings, particularly pigments, etc., if their surfaces are chemically inert, can not be thoroughly dispersed in vehicles, etc. In this situation, in order to improve the chemical property of the powder surface, its surface treatment by use of low temperature plasma has been contemplated. For such low temperature plasma treatment of powders, a method of treating powders with low temperature plasma, while rotating or swinging a drum in which they are put, or a method of treating powders with low temperature plasma, while stirring them by such a means as an impeller, magnetic stirrer, etc., and so forth appear, for example, in Unexamined Patent Publication Nos. 56-155631, 57-177342, 58-205540 and 59-145038. However, depending on the type of powders, when a method such as by stirring, rotating, swinging, or the like is used, the so-called granulation, or coagulation of a plurality of powders into one lump, or cohesion of powders on the vessel's inside wall surface tends to occur; thus it was difficult to make uniform and efficient treatment.